Patent GB-1014680-A (GB)
Title: Improvements in or relating to apparatus for calculating the weighted average of twoor more numbers
Inventor: JOHNSON IVAN BORIS DAVID
IPC: G01M1/12
Filed: 1963-04-18
Abstract: 1,014,680. Electric analogue calculating. S. SMITH & SONS (ENGLAND) Ltd. April 10, 1964 [April 18, 1963], No. 15217/63. Heading G4G. Apparatus calculating the weighted average of two or more numbers comprises a series of resistors connected across a voltage source to represent in resistance value the numbers in the order A 1 , A 2  . . . A r  . . . A n ; B q , B q-1  . . . B p  . . . B 1 ; the junction of resistors representing A n , Bq being connected to a first terminal and the junction of every other pair of adjacent resistors representing A r  and A r-1  or Bp and B p-1  being connected to a second terminal over a corresponding resistor of conductance pro. portional to a r  - a r-1  or b p  - b p-1  respectively; with the ends of resistors representing A 1  and B 1  connected to the voltage source being connected to such second terminal over resistors of conductances proportional respectively to a 1  and b 1 . Then the voltage occurs the first and second terminals represents the weighted average where A 1  to A n  and B 1  to Bq are the numbers and a 1  to an and b 1  to bq are the weightings applied thereto, and a r A r  is positive while b p  B p  is negative r is any integer between 1 and n p is any integer between 1 and q a 1 <a 2  . . . <a r  . . . <a n  b 1 <b 2  . . . <b p  . . . <b q  An aircraft assumed to be equivalent to a beam axis 15 (Fig. 1), pivoted about datum 16 carries fuel weight W 1  in forward tanks, displaced a distance a forward of datum; fuel weight W 3  in wing tanks displaced a distance c+d aft of datum; fuel weight W 2  in after tanks displaced a distance b+c+d aft of datum; and the tare weight W 4  of the aircraft operates through its C. G. displaced a distance d aft of datum. Four series variable resistors 1, 2, 3, 4 (Fig. 2), are connected across a voltage source 5, 6; and terminal 5, the junction of resistors 2, 3, the junction of resistors 3, 4, and terminal 6 are connected over respective resistors 7, 8, 9, 10 to input 12 of a difference amplifier 11, whose remaining input 14 is connected to the junction of resistors 1, 2 over resistor 13. Resistor 1 is varied in value in accordance with the fuel weight in the forward tanks and resistor 7 is varied in conductance by the displacement of the C. G. of the forward fuel tanks from datum. Resistor 4 is varied in value in accordance with the aircraft tare weight and the conductance of resistor 10 in accordance with the displacement of the aircraft C.G. from datum. Resistor 3 is varied in value in accordance with the fuel weight in the wing tanks and resistor 9 is varied in conductance according to the displacement of the C. G. of the wing fuel tanks from that of the aircraft. Resistor 2 is varied in value in accordance with the weight of fuel in the aft tanks and resistor 8 is varied in conductance according to the displacement of the C. G. of the aft fuel tanks from that of the wing fuel tanks. The fuel weight variable resistors may be linked to fuel gauges. Then in the above formula W 1 αA 1  aαa 1  W 4 αB 1  dαb 1  W 3 αB 2  (c + d)αb 2  W 2 αB 3  (b+c+d)αb 3  and resistors 7, 8, 9, 10 have conductances respectively representing a 1 , (b 3 -b 2 ), (b 2 -b 1 ), and b 1  so that the output of the difference amplifier represents h and is proportional to the distance of the total C.G. from datum. The amplifier output may operate an indicator and may control valves in the fuel flow from the several tanks to maintain the C. G. at datum or at a predetermined distance therefrom. Resistors 1, 2, 3 may be controlled by flowmeters representing the weights of fuel in the several tanks. The position of the total C. G. may be measured by apparatus wherein the fuel weights are determined by fuel gauges, and by other apparatus wherein the fuel weights are determined by flowmeters, and a warning signal may be operated if the C. G. positions calculated by each apparatus differ by more than a predetermined margin.